Kristy trailer has a few intersting things to see...

https://www.youtube.com/watch?v=OZK6ZiiOUuk

For starters, 12 seconds in you can see a snippet of the cult killing the gate guy which is something completely absent from the released cut. Also you see more shots of the forum the cult posts on and some unused clips from Justine's "misadventures on campus" montage. With regards to the first one I'm sure that's not the only thing cut from release and that sucks as I'd love to see all the deleted scenes for this.

Also, just me analyzing but if you actually pause the trailer when it shows the forum posts (plus read the few seen in the film), it seems to be implied (to me anyway) they really aren't some weird ass cult as much as just a bunch of messed kids looking to cause trouble and spread fear. The posts glorify snuff films and the discussion goes to them wondering if anyone would have the balls to do it in real life. Makes me wonder if things changed as the film progressed or they just threw those forum posts images up without thinking anyone would read them or take them seriously. The whole concept with "Kristy" is just their gimmick for their own fun seeing as they film their prey as well as them dying since they are snuff film fans. Probably nothing but it appears that way if you read the posts then watch the film again.